| 摘要 |
PURPOSE:To contrive high integration, speeding up, and low costing of the title device by bringing an impurity layer (collector layer) formed after diffusing at a substrate into contact with a conductive substance buried inside of trenches that are used for isolating elements, thereby taking out its layer as electrodes. CONSTITUTION:An N-type diffusion layer 13 is formed and trenches 16 are formed by removing a P-type Si substrate where an SiO2 film 15, a nitriding film 14, and a thermal oxide film 12 are deposited after etching them. And then, a P is diffused in the Si substrate from contacting parts 23 between phosphorus-doped polysilicon 20 filling the trenches 16 and a silicon through a prescribed deposition and an etching process and N-type diffused layers 24 are formed. In this way, phosphorus-doped polysilicon 20 in the trenches and the impurity diffusion layer 13 are electrically connected each other to lower a collector resistance of a bipolar transistor that is formed by a process mentioned in the latter. Then a base layer is formed by ion-implanting B in the prescribed region and then, an emitter diffusion layer is formed by diffusing As in the substrate after ion-implanting As. In such a case, simultaneously B is diffused from polysilicon to lower the resistance of a base diffusion layer. Further, an inter layer insulating film is formed by depositing the SiO2 film. Consequently, an etching treatment is carried out in a state of the prescribed shaped to form base, emitter, and collector electrodes 30, 31 and 32 respectively.
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